move implementation to internal/ directory (#828)

internal/pruning/keep_not_replicated.go

@@ -0,0 +1,13 @@
+package pruning
+
+type KeepNotReplicated struct{}
+
+func (*KeepNotReplicated) KeepRule(snaps []Snapshot) (destroyList []Snapshot) {
+	return filterSnapList(snaps, func(snapshot Snapshot) bool {
+		return snapshot.Replicated()
+	})
+}
+
+func NewKeepNotReplicated() *KeepNotReplicated {
+	return &KeepNotReplicated{}
+}